U.S. Secretary of Defense Chuck Hagel speaks to service members and civilian employees on his first day in his new post after being sworn in at the Pentagon in Arlington on Feb. 27. (JONATHAN ERNST/REUTERS)

Chuck Hagel appeared more at ease during his first day on the job at the Pentagon on Wednesday than he did during his turbulent confirmation process, as he repeatedly paid homage to a military that has been engulfed in war for nearly 12 years.

Hagel, who was sworn in earlier in the day, is the only Vietnam combat veteran to serve as defense secretary. In his remarks Wednesday, the former enlisted infantryman didn’t dwell on his experience or the two Purple Hearts he was awarded for being wounded in combat. But his military service colored his pledges to the troops to “do everything I can to ensure the safety, the well-being, the future for you and your families.”

“I’ll never ask anyone to do anything I wouldn’t do,” he told a packed auditorium at the Pentagon in an address that was televised to U.S. military personnel worldwide. “You’ll always know that you have a secretary of defense that will deal straight with you. I’ll be honest. I’ll be direct. I’ll expect the same from you.”

Hagel was confirmed by the Senate on Tuesday in a 58-41 vote, the narrowest approval ever for a defense secretary nominee. Some senators who opposed him — all fellow Republicans — have questioned whether his wartime service in Vietnam would make him overly reluctant to send U.S. troops into new conflicts, citing his opposition to the surge in Iraq.

Hagel did not address that criticism directly but described his foreign policy beliefs in broad terms.

“We can’t dictate to the world, but we must engage with the world,” he said. “That engagement in the world should be done wisely. And the resources that we employ on behalf of our country and our allies should always be applied wisely.”

That philosophy led Hagel to become close with President Obama when they served in the Senate, despite their party differences. Although Obama redoubled U.S. involvement in the war in Afghanistan, he has been reluctant to intervene militarily in Syria, Libya and other hot spots.

Shortly after he was sworn into office during a private ceremony, Hagel visited the Pentagon memorial to the victims of the Sept. 11, 2001, attacks. “In Churchill’s words long ago, that was ‘a jarring gong,’ that event, that set in motion dynamics that we are living with today,” he said.

Addressing the troops and civilians at the Pentagon, Hagel reminded them that the U.S. military has been embroiled in long-running conflicts that reach back further. He noted that the first Persian Gulf Warended almost 22 years ago, on Feb. 28, 1991.

“If you take those two events and start charting this, not unlike history, you start to see a picture emerge of different kinds of threats,” he said. “Not that any of us, I don’t think, are smart enough to know it all or figure it all out, but it gives us some dimension of what’s going on in the world.”

More immediately, the Pentagon is bracing for the likelihood that it will have to cut $46 billion from its annual budget under the sequester that is slated to start Friday, unless Congress and the White House find another way to reduce the federal deficit before then. Military leaders have warned that they will have to cut back severely on training and maintenance and will be forced to furlough as many as 800,000 civilians.

Unlike his predecessor, Leon E. Panetta, who didn’t waste an opportunity to warn that the cuts would mean “doomsday” for the military, Hagel told his audience that the Pentagon would have to cope with “dollars coming down.”

“It’s the uncertainty of the planning, it’s the uncertainty of the commitments, the uncertainty of what’s ahead,” he said. “We need to figure this out. . . . We need to deal with this reality.”